This study proposes an internal discharge drilling cuttings method and corresponding drilling tools as a solution to inaccurate collection of drilling cuttings in existing drilling cuttings methods. Its mechanism is to transport drilling cuttings out of the hole tiorough the internal channel of the drilling tool by negative pressure. The drilling cuttings were collected and weighed. Their transportation patterns under negative pressure were analyzed via theoretical analysis.The CFD-DEM coupled numerical simulation was conducted to study how different structures of transportation channels influence the drilling cutting-gas flow. The drilling rod was processed based on the numerical simulation results. Laboratory experiments were conducted to verify the feasibility of drilling cuttings collection by the internal discharge drilling cuttings method. Results indicate that 1) Higher pressure differences lead to faster transportation of drilling cuttings; 2) Under the same negative pressure and drilling speed, the cross-sectional size of the fluid hole at the end of the drilling tool is directly proportional to the efficiency of drilling cuttings transportation under negative pressure; 3) Increasing the number of fluid holes could promote the efficiency of drilling cuttings transportation under negative pressure; 4) When the fluid hole is tilted 30 degrees towards the drill bit, it exhibits the optimal transportation performance of drill cuttings under negative pressure.

To explore the occurrence mechanism of compound dynamic disasters in coal rocks, this study conducted a true triaxial test simulating gas extraction and stress loading and unloading conditions. To differentiate behaviors among disaster types, the effects of acoustic emission energy, temperature and impact force were analyzed during disaster incubation. The results revealed that different simulation depths lead to varying types of compound dynamic disasters. Compared to rockburst-outburst compound dynamic disasters, outburst-rockburst compound dynamic disasters exhibited higher relative outburst intensity and critical gas pressure. Deep coal rock disasters were characterized by long incubation and short excitation. As a threshold for disaster type transformation, a critical gas pressure range of 2.2-2.8 MPa was identified. During incubation, the temperature generally increased, with greater variation in the coal seam than at the coal-rock interface. During excitation, the temperature dropped sharply, with smaller variation in the coal seam. Outburst-rockburst disasters consistently showed higher temperature variation than rockburst-outburst disasters. Impact force evolution in roadways followed a similar pattern across disaster types: initial impact → intensification → peak → attenuation, with a peak effect. The peak impact force increased linearly with critical gas pressure, with outburst-rockburst peak growth rates being 47.76 times higher than rockburst-outburst peak growth rates. This study provides important insights into the multi-parameter evolution characteristics of deep coal rock compound dynamic disasters, offering a scientific basis for disaster prediction and control.